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Setting idle

Discussion in 'Boxers/TR/M' started by Guss23, Apr 1, 2021.

  1. Guss23

    Guss23 Karting

    Jun 11, 2017
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    Indianapolis
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    Jason Sharkey
    I’m trying to set the idle on my 86 TR. i’m using a vacuum gauge. I’m getting about 22 inches on the driver side and about 17 inches on the passenger side. I’m also not seeing a lot of movement when delicately adjusting the idle knob. Am I doing something wrong?
     
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  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #2 Steve Magnusson, Apr 1, 2021
    Last edited: Apr 1, 2021
    (If a US version) With both air bypass screws fully closed, adjust the throttle plates to give equal vacuum in the two plenums and ~700 RPM warm idle (opening a throttle plate will reduce the vacuum and increase the engine RPM, while, likewise, closing a throttle plate will increase the vacuum and lower the engine RPM). Then open each air bypass screw to get 1000~1050 RPM warm idle and still equal vacuum in the two plenums (this should be something like 1/2~1 turn on each air bypass screw, not 3~4 turns). Also, I wouldn't trust the tach in the dash too much -- use a Hz meter on the flywheel RPM sensor output (2433 Hz = 1000 RPM) or a timing light with an RPM function. A final check (once happy with ~1000 RPM warm idle and equal vacuums) is to use the throttle cable to raise the engine speed to ~2500 RPM and ensure the vacuums are still about equal (if not, then you have to muck with the various linkages).

    PS I wouldn't tweak anything until ensuring that both AAVs are fully closed at warm idle and the protection relay is working.
     
  4. jgmblair

    jgmblair Formula Junior

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  5. Guss23

    Guss23 Karting

    Jun 11, 2017
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    Jason Sharkey
    Thank you. How do you adjust the throttle plates?
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    By turning screws 1 in Fig 78 on page D101 of the TR WSM (item 50 in the SPC link below) -- and you might need to break off the plastic anti-tamper plug (or, better, cap) -- item 52 here:

    https://www.ferrariparts.co.uk/diagram/ferrari/testarossa-tr-90/018-throttle-control

    if it hasn't been mucked with before. But please see the PS in post #2 before tweaking them.
     
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  8. Veedub00

    Veedub00 F1 Rookie
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    ugh, I wouldn't mess around with the throttle plates. way too sensitive and try everything else first. and it sounds like you are a novice given your questions you have already asked, so definitely don't mess those up, you'll end up taking it into the dealer to get fixed.
     
  9. Guss23

    Guss23 Karting

    Jun 11, 2017
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    Jason Sharkey
    When you have the bypass screws closed how much vacuum should there be?
     
  10. Veedub00

    Veedub00 F1 Rookie
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    do you have the manual? search on here for it. You need the KE Jetronic addendum for US cars. there's a procedure to follow.
     
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  11. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #9 Steve Magnusson, Apr 2, 2021
    Last edited: Apr 2, 2021
    Went thru my notes, and haven't written this down, but, IIRC, it isn't anything hugely different from the 1000 RPM vacuum (maybe a little lower, but not sure about that?).

    The 1000 RPM warm idle vacuum will depend on your barometric pressure (e.g., your elevation above sea level) and the accuracy of your gauge(s) -- I have two, and they differ by 1~1.5 in. Hg (so I just use one to measure each bank). Last time I did this (~740' elevation), I had about 16 in. Hg at 1000 RPM warm idle (on the vacuum gauge I selected to use ;)).

    Were/are your plastic anti-tamper caps still in place on the throttle plate adjustment screws, or had someone been in there before and not replaced them?
     
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  13. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Forgot to add that you should make sure it is running on both banks (it will still run very smooth on a single bank). You never indicated WHY you are trying to set the idle -- if the symptom was/is it went from idling at 1000 RPM to something a lot lower in a sudden shift of behavior = more likely a dead bank.
     
  14. Guss23

    Guss23 Karting

    Jun 11, 2017
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    Yes, both banks are running. So if the drivers bank is creating 22 inches and the passenger is generating 17 inches at 1000 RPM what should I do? Seems like a dramatic difference. It seems to start perfectly, hot or cold. Seems to idle a bit high. 1500 RPM
     
  15. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #12 Steve Magnusson, Apr 2, 2021
    Last edited: Apr 2, 2021
    The procedure is in post #2 -- you are unbalanced now.

    First, unplug the throttle microswitch when at the ~1500 RPM warm idle = the idle speed should increase to maybe 1800~2000 RPM. If it doesn't, your throttle microswitch is either misadjusted or bad -- this would need to be fixed before doing anything else. If it does (correctly) go up when unplugged, plug it back in and fully close the air bypass screws (note how many turns needed to close them as a piece of data about the "before" condition) -- if the two banks are still unbalanced with both air bypass fully closed, you would adjust the throttle plates, as needed, to get the 700 RPM warm idle and equal vacuums (however, you need to ensure that the throttle microswitch is not restricting the 1-6 throttle plate motion yet the idle switch portion is still electrically closed when at idle). Then open each air bypass screw to get 1000~1050 RPM warm idle and still equal vacuum in the two plenums (this should be something like 1/2~1 turn on each air bypass screw, not 3~4 turns). When done, again unplug the throttle microswitch at idle and confirm the idle RPM increases.

    I'm starting to agree with James -- have you read Chapter D (thru page D106) of the TR WSM? Do a search on "121517" for more threads about the throttle microswitch used on US TR.
     
  16. Guss23

    Guss23 Karting

    Jun 11, 2017
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    I’ve tried resetting it twice and continue getting the same results. Vacuum pressure on the driver side is still 25 inches in the passenger side it’s about 15 inches. It idols out OK but stumbles and trips at about 3500 RPM under load. It doesn’t do it when it’s in neutral.
    I checked all the spark plug cables with the timing light. They all seem to work. I figure the problem is probably either in the fuel feed (fpr) Or possibly fouled spark plugs. Thoughts?
     
  17. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #14 Steve Magnusson, Apr 3, 2021
    Last edited: Apr 3, 2021
    Not good (nor proper) -- the vacuums are meant to be adjustable to be equal. Why can't you make them more equal? Are you monitoring the unplugged O2 sensor voltages when making the adjustments to ensure the mixtures are roughly reasonable (i.e., a little rich - say 0.6V to 0.9V)?
     
  18. Guss23

    Guss23 Karting

    Jun 11, 2017
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    I will try that
     
  19. Guss23

    Guss23 Karting

    Jun 11, 2017
    76
    Indianapolis
    Full Name:
    Jason Sharkey
  20. Guss23

    Guss23 Karting

    Jun 11, 2017
    76
    Indianapolis
    Full Name:
    Jason Sharkey
  21. Guss23

    Guss23 Karting

    Jun 11, 2017
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    Jason Sharkey
    Is there an easy way to test the AAV?
     
  22. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    "Pinch" one of the air lines of the AAV closed during warm idle (simulating a fully closed AAV) -- the idle RPM should not change; if the idle RPM does go down, the AAV is not fully closed as it should be when warm.
     
  23. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Yes. The black plastic piece is the anti-tamper cap 111182 -- it is virtually impossible to remove it without breaking it (so either the throttle plate adjustment screws have never been mucked with, or someone mucked with them then put on fresh anti-tamper caps). If your AAVs are OK and fully closed when warm, check to see if the vacuums are equal, or unequal, when the air bypass screws are fully closed (the idle speed should be ~700 RPM).
     
  24. 2dinos

    2dinos F1 Rookie

    Jan 13, 2007
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    #21 2dinos, Apr 4, 2021
    Last edited: Apr 4, 2021
    Lots of demos of procedure on Youtube,

    FWIW: I started with large instrument quality dial vac gages. That was a bust! No where near the accuracy or resolution. Also, as Steve mentioned, the tach in the dash had me chasing around wasting time as well. Use an accurate external tach.
     
  25. ago car nut

    ago car nut F1 Veteran
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    I used a quality vacuum gauge with a 2 port mechanical valve. One hose to the gauge, two hoses, then to each bank. Manometer is probably the best.
     
  26. dwhite

    dwhite F1 Rookie

    I have a BBi and when I did this. The first thing I did was disconnect the linkage from each throttle body. You first need to establish that the throttle plates are set identical and the linkage is correct. If not you will be chasing your tail.
     
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